Its based on random techniques to provide you a new or old anonymous account, but not from other device. Suppose you've created an anonymous account from your mobile device and everytime you go through anonymous sign process reach to an unknown new account but its too possible that you may someday sign into any of your history accounts. Its actually based on your device keys. I don't know how but it works this way as explained by @infeeds official account.

Its fun to use, share and vote things with anonymous identity that you don't even know about how to handle.